Antistatic photographic film

ABSTRACT

ANTISTATIC AGENTS FOR USE WITH FILM-FORMING ORGANIC BINDERS COMPRISING THE CONDENSATION PRODUCT OF AN ALKYLENE OXIDE HAVING FROM 2 TO4 CARBON ATOMS WITH 2,4,7,9TETRAMETHYL-5-DECYNE 4,7-IDOL, SAID CONDENSATION PRODUCT HAVING A MOLECULAR WEIGHT OF AT LEAST 300.

United States Patent Oflice 3,625,695 Patented Dec. 7, 1971 3,625,695ANTISTATIC PHOTOGRAPHIC FILM E. Scudder Mackey, Binghamton, N.Y., andHarvey Abend, Lexington, Ky., assignors to General Aniline & FilmCorporation, New York, N.Y. No Drawing. Filed May 9, 1967, Ser. No.637,096 Int. Cl. G03c 1/82 U.S. Cl. 96-84 A 4 Claims ABSTRACT on THEDISCLOSURE Antistatic agents for use with film-forming organic binderscomprising the condensation product of an alkylene oxide having from 2to 4 carbon atoms with 2,4,7,9- tetramethyl-S-decyne 4,7-diol, saidcondensation product having a molecular weight of at least 300.

The present invention relates in general to photography and inparticular to photographic film materials possessed of superiorantistatic properties, as well as to the provision of novel compositionsfor such purposes.

One of the problems frequently encountered both in the manufacture anduse of photographic film elements relates to the pronounced and highlyobjectionable tendency of such elements to acquire as well as toaccumulate intolerable quantities of static electricity. The level ofstatic build-up is unavoidably influenced to a great extent by theconditions employed during the manufacture of the film base, i.e., thesheet materials serving as the support for the emulsion layer as well asthe coating operations associated with the subsequent deposition of oneor more layers upon such film base, e.g., subbing layers, lightsensitivelayers, etc. The generation of static electrical charges can also occurto a significant extent as a result of trimming and packagingoperations, by manipulation of the film element in camera mechanisms andparticularly, motion picture cameras, cameras utilized for X-rayfluorography, i.e., wherein a sequence of exposures is taken in rapidsuccession.

The significance of the foregoing phenomena can be made readily evidentby reference to the following discussion. As is well known, in themanufacture of multilayer photographic film elements, a film base iscoated on one or both sides with for example, a subbing compositionusually comprising a dispersion of gelatin in a suitable solvent orsolvent mixture, the latter serving to facilitate the adherence oranchorage of subsequently applied layers, e.g., photosensitive,non-curling; antihalation layers, and the like. When such a laminate iswound into a tight curl and subsequently unwound, considerable staticelectricity is generated and spark discharges are likely to occur. Theforegoing phenomena is invariably manifested following development ofthe exposed film in the form of black streaks, lines, or otherirregularities which tend to create a fog pattern throughout the entireemulsion layer. In general, such spurious density deposits become morepronounced as the sensitivity and thus speed of the film material isincreased. Consequently, the provision of more efiicient sensitizingagent has made incumbent upon the film processor the inclusion in thefilm element of one or more substances which abate, or otherwise, retardthe tendency of such film to accumulate such static charge oralternatively, a substance which is essentially an electrolyte orpossesses hygroscopic properties in order to impart conductivity to thefilm element and thereby expedite dissipation of such static chargesbefore their accumulation leads to local electrical discharges. It willbe readily appreciated that the aforementioned spurious density depositsare objectionable, not only from the standpoint of quality, orreproduction but, more importantly, can be dangerously misleading aswould be the case, for example, with medical X-ray films. It is ofcritical importance with respect to the latter materials that the imageobtained constitute a reliable and unimpeachable record of theinformation recorded. Even the slightest departures of the emulsionmaterial from optimum sensitometric characteristics, as well as anytendency of the film to reflect static charge built-up in the form ofspurious density deposits may lead to serious consequences.

Despite the efforts of prior art investigators to devisefilm-manufacturing techniques, as well as coating methods which wouldtend to minimize or suppress any possibility of static charge build-up,such problems have nevertheless persisted to challengefilm-manufacturing and processing technology. For example, it is oftenfound that the fugitive effects directly attributable to static chargebuild-up are very much in evidence as a result of mere contact of thefilm with the gate of the film projector or other parts of the apparatuswhich the film may frictionally engage during its course of travelthrough the projector device.

Concomitant with the provision of silver halide emulsions possessed ofunusually high photographic speed, has

een a corresponding intensification of the antistatic problem. Many ofthe film materials currently available commercially and specifically andbeneficially adapted for use in connection with high speedphotoreproduction techniques involve, as required processing, the use ofhigh activity photographic processing solutions, e.g., developer, fixer,etc. As will be recognized, even the slightest tendency of thephotographic film element to accumulate static charge will practically,without exception, result in the formation of irregularities in theimage-recording emulsion, i.e., defects of the type describedhereinbefore. Successful negotiation of the antistatic problem hascorrespondingly tended to circumscribe severely the emulsionmanufacturers scope of operations with respect to the choice of theingredients to be included in the emulsion as well as non-sensitizedlayers of the photographic film element.

In an effort to overcome, or otherwise alleviate the problems associatedwith static electricity build-up on photographic films, considerableindustrial activity has centered around the research and development ofsubstances which could be conveniently included in one or more of thelayers present on the photographic film, such substances possessing thesingular property of promoting static charge dissipation, or otherwiseaugmenting the ability of the film element to resist static build-up. Ingeneral, such compounds function to reduce the resistivity, i.e., toimpart conductivity to the film element and thus to expedite staticelectricity dissipation prior to discharge and spot exposure of theemulsion. According to recognized practice, such substances are mosteffectively provided in the form of a film-forming composition utilizinga suitable organic binder material, e.g., resin, colloid, etc., fordirect application to the photographic film base as a backing layer.Thus the antistatic compound may be included as a component of anantihalation and/or anticurl, the latter being provided on the oppositeside of the film base material, i.e., opposite the light-sensitiveemulsion side. Despite the fact that the vast majority of the antistaticcompounds thus far promulgated in the art for the aforedescribedpurposes have led to significant reductions in antistatic build-up, aswell as residual charge retention, the overall improvement realizedthereby has nevertheless been somewhat marginal in the aggregate. Thesub-optimum effects of such compounds in this connection resultsprimarily from their tendency to otherwise deleteriously affect thephotographic film element. In ideal terms, it is imperative that theantistatic compound in no way detract from the strength of adhesionrequisite to firm bonding of the backing layer to the film base. Failurein this regard inevitably leads to undesired separation of the backinglayer from the film base. This phenomenon often referred to in the artas dry peel undesirably characterizes a considerable number of theantistatic compounds heretofore provided. It is likewise of criticalimportance that the antistatic compound exhibit absolutely no tendencyto generate, or otherwise contribute, to the formation of foam inpost-exposure processing solutions and particularly those solutionsagitated with gas bursts. Quite obviously the existence of foam tends tovitiate any possibility of achieving uniform and intimate contacting ofthe photographic processing solution with exposed emulsion layer. Again,the emergence of high speed processing has correspondingly rigidifiedthe requirements in this respect. In addition to the aforedescribeddesiderata, it is of considerable importance that the antistaticsubstance be devoid of any tendency to adversely affect the physicalappearance of the emulsion layer, e.'g., to cause matting, streaking,etc. Furthermore, it is of equal importance that the antistatic compoundbe totally inert with respect to the sensitometric properties ofthephotographic film and thus display absolutely no photoactivity.Despite the relatively vast number of compounds provided in the art forpurposes of imparting optimum antistatic behavior to photographic filmelements, such compounds are nevertheless invariably found to bedeficient in one or more of the aforedescribed aspects. Thus, the use ofsuch compounds usually necessitates resort to the use of additionalauxiliary ingredients designed to compensate for the shortcomings ofsuch antistatic agents, e.g., antifoaming agents, antifoggants,sensitizing agents, adhesion promoters and the like. Such correctiveprocedures can obviously be quite costly, if not prohibitive.

In accordance with the discovery forming the basis of the presentinvention, it has been ascertained that the use of a rather specific anddelimited class of acetylenic diol derivatives makes possible theprovision of backing layers for photographic film elements havingoutstanding antistatic properties, said compounds being totally devoidof any tendency to deleteriously affect the sensitometric properties ofthe emulsion layer.

Thus, a primary object of the present invention resides in the provisionof improved antistatic compositions wherein the foregoing and relateddisadvantages are eliminated or at least mitigated to a substantialextent.

Another object of the present invention resides in the provision ofimproved film-forming antistatic compositions capable of readydeposition to photographic film base materials in the form offirmly-bonded layers.

A further object of the present invention resides in the provision offilm-forming antistatic compositions which are totally devoid of anytendency to detract from the sensitometric properties of photographicelements provided with the same. 7

A still further object of the present invention resides in the provisionof improved antistatic compositions which may be employed to advantagein the preparation of antihalation and anti-curl backing layers forphotographic film elements.

Other objects and advantages of the present invention 4 will becomeapparent hereinafter as the description proceeds.

The attainment of the foregoing and related objects is made possible inaccordance with the present invention which in its broader aspects,includes the provision of antistatic compositions comprising (a) a filmforming organic binder, i.e., protective colloid, and (b) an antistaticcompound comprising the condensation product of an alkylene oxide with2,4,7,9-tetramethyl-5-decyne 4,7- diol said condensation productscorresponding to the following structural formula:

wherein m and it together represent integers such as to provide amolecular weight Within the range of from about 300 to about 150,000 ormore, and wherein R and R represent alkylene of 24 carbon atoms, e.g.,ethylenepropylene, etc.

Particularly beneficial results are found to obtain in accordance withthe present invention wherein R and R in the above formula representethylene, such products corresponding to the following structuralformula:

halation function. Accordingly, the film-forming binder may be either ofa permanent or temporary nature. In the latter case, resin materials areselected which, though water-insoluble, nevertheless exhibit readysolubility in aqueous alkaline media thus assuring ready removal of thebacking layer during post-exposure processing, e.g., developerimmersion. Should an antihalation utility be contemplated for thebacking layer, the antistatic agent composition will be provided withone or more of the dye stuff materials customarily employed in the artfor such purposes. In this connection, reference is made to thedyestuffs described, for example, in US. Pats. 1,805,404; 2,036,546;2,150,695; 2,282,890; 2,304,946; 2,598,660; 2,606,833; 3,264,108; etc.Although any of the aforereferenced dyestuff materials may be employedto advantage in the practice of the present invention salient advantagehas nevertheless been determined to obtain with antihalation dyestuffsof the type described in US. Pat. 2,598,660, such dyestuffscorresponding to the following structural formula:

wherein n represents an integer from 2 to 10 inclusive, Y represents asubstituent selected from hydrogen, lower alkyl, halogen, nitro, sulfo,carboxy, earbalkoxy and alkoxy, and A represents an anion of a strongmineral acid, or, alternatively, an internal linkage wherein Yrepresents sulfo or carboxy, and wherein R and R represent lower alkyl,e.g., methyl, ethyl, propyl, etc.; hydroxyalkyl, and omegahydroxypolyoxyalkyl.

The aforementioned dyestuffs are found to present particular advantagein that they are readily and easily decolorized as a concomitant ofphotographic processing and furthermore, exhibit highly favorablesolubility characteristics, i.e., can be readily dissolved away from theantihalation layer in the normal course of post-exposure processing,i.e., developing, fixing, washing, etc.

The film-forming binder component of the backing layer coatingcomposition conventionally termed protective colloid may be selectedfrom any of those well-known in the art for such purposes, with theselection of a particular one being determined largely by the ultimatecharacter contemplated for the backing layer, i.e., whether permanent ortransitory, as previously mentioned. In the latter case, any of thewater-insoluble, alkali-soluble resin film formers may be used withspecific representatives including, for example, copolymers of alkylmethacrylates and methacrylic acid; the carboxy resinic lactones, thepolyvinyl phthalates, the polyvinyl acetate phthalates, and the ethylcellulose phthalates. Other suitable resins include the celluloseorganic acid esters containing dicarboxylic acid groups such ascellulose acetate phthalate, cellulose acetate maleate, celluloseacetate succinate, cellulose acetate propionate phthalate, celluloseacetate propionate maleate, and cellulose acetate propionate succinate.The above-enumerated resins and their method of preparation are wellknown in the art, being extensively described in the literature, bothpatent and otherwise.

In those instances wherein the backing layer is to be of a permanentnature, it is preferred practice, in accordance with the presentinvention, to employ as the filmforming binder, a composition comprisingat least 50- 50% gelation with the remainder comprising, for example, asynthetic polymeric substance of the type hereinbefore mentioned.

In order to assure the obtention of optimum results, it is advisable toemploy the polyoxyalkylenated butyne diol antistatic compound inconcentrations ranging from about 2% to about by Weight, based on thewe1ght, of film-forming binder e.g., gelatin, with a range of 3- 6%being particularly preferred. In any event, it will be understood thatthe antistatic agent, apart from the requirement of being present inamounts sufficient to yield the desired conductive character to thebacking layer, is not of critical importance to the realization of theadvantages described herein. Thus, it will be envisaged that particularcircumstances and requirements of the processor may dictate departuresfrom the aforestated range.

Other ingredients, strictly of an optional nature, which may be includedin the backing layer coating composition for purposes of augmentingadhesion strength, stability and the like, include, for example,hardening agents, e.g., formaldehyde, glyoxal, mucochloric acid, etc.,coating aids such as saponin or other materials promulgated in the artfor such purposes. Again, it must be emphasized that nothing criticalattends the selection of the lattermentioned ingredients, their identityand use being common knowledge in the art. At this point, it should bestressed that the antistatic agents of the present invention possess thehighly desirable property of relatively unlimited compatibility with thevast majority of compounds promulgated in the art for the preparation ofphotographic film backing layer compositions, whether such be intendedfor use as an antihalation, anti-curl or other purposes.

The film base materials to which the antistatic compositions of thepresent invention may be applied encompass a wide variety of substancesincluding, for example, cellulose organic esters such as celluloseacetate, or cellulose nitrate; film-forming polymeric materials such aspolyvinyl chloride; polyamides; polyesters such as those obtained by thecondensation reaction of a dicarboxylic acid with a dihydric alcohol;polycarbonates, and the like.

The advantage made possible by the present invention will be mademanifest by reference to the following examples. However, it will beunderstood that such examples were given for purposes of illustrationonly, and are not to be considered as necessarily constituting alimitation on the present invention.

EXAMPLE I An antihalation coating composition of the type conventionallyemployed in the photographic arts as a backing layer for light-sensitivephotographic elements is prepared by adding to 10 liters of an aqueousgelatin solution (10% gelatin), 10 gms. of saponin as coating aid, 10gms. of formaldehyde (hardening agent) and 16 gms. of the antihalationdyestufr described in Example 1 of US Pat. 2,598,660, said dyestutfhaving the following structural formula:

I-I(OCH OH (CH CH OMH 4 [p bis(8 hydroxy 3,6 dioxaoctyl)amino-aphenylbenzylidene] 2,5 cyclohexadienylidene [bis(8hydroxy-3,6-dioxaoctyl) imonium chloride.

The composition is adjusted to a pH of 5.6 in order to achieve mosteffective dye strength. The coating composition thus obtained is dividedinto three parts identified as (a), (b) and (c) respectively. Part (a)is coated onto one side of a cellulose acetate photographic film base byconventional techniques and serves as the control sample. To part (b),is added 3% based on gelatin solids, of a condensation product ofFormula II given hereinbefore, said product comprising the reactionproduct of 10 mols of ethylene oxide with 2,4,7,9-tetramethyl-5-decyne4,7-diol. The latter product is available commercially under the tradename designation Surfynol 465. The composition so constituted isthereafter coated onto a cellulose acetate photographic film base. Topart (c) is added 3% based on gelatin solids, of a condensation productof Formula II above, comprising the reaction product of 30 mols ofethylene oxide with 2,4,7,9-tetramethyl-5-decyne 4,7-diol. The latterproduct is available commercially under the trade name designationSurfynol 485. The composition thus prepared is likewise applied to aphotographic film base. Each of the coated samples, after drying, isconditioned in an atmosphere of 50% relative humidity for a period of 12hours. Resistivity measurements of the coatings are then made by thecommon parallel electrode technique. The results obtained are itemizedin the following table:

TABLE I Ohms Controlpart (a) x10 Sample containing Surfynol 465part (b)25X 10 Sample containing Surfynol 485-part (c) 24 l0 As the above datamakes manifestly clear, the antistatlc compounds of the presentinvention make possible at least a five-fold decrease in resistivity ofthe photographic film base when compared to the control sample. Thesignificant increase in conductivity of such layers allows any staticcharge accumulated by photographic elements coated therewith to beuniformly dissipated to the extent that only negligible residual chargeremains with the correlative advantage that deleterious effects upon thequality of image photoreproduction which would otherwise obtain as adirect result of the presence of such static charge, are completelyeliminated.

7 EXAMPLE II Example I is repeated except that each of the coated filmbase materials identified as (a), (b) and (c) respectively, is furtherprovided on the side opposite the backing layer with a conventionalphotographic silver halide emulsion in gelatin containing 4% silveriodide and 96% silver bromide. After drying, each of the samples isexposed in a Type 1-B Sensitometer and developed in a photographicdeveloper of the following composition:

Grams Metol 1.5 Sodium sulfite, anhydrous 45.0 Sodium bisulfite 1.0Hydroquinone 3.0 Sodium carbonate, monohydrated 6.8 Potassium bromide .8

Water to make 1.0 liter.

An inspection of sample (a) reveals the existence of a rather highpopulation of spurious density deposits, or other irregularities whichdetract considerably from the overall appearance of the final image. Incontradistinction, the prints obtained with samples (b) and (c)respectively, are completely devoid of such fugitive density depositswhether in the form of streaks, lines, or other irregularities. Inaddition, no evidence of emulsion fog is detected. It is also observedthat the backing layer exhibits absolutely no tendency to separate fromthe photographic film base, i.e., is firmly-bonded to such film base,despite continued subjection to the post-exposure processing media,e.g., developer, fixer, etc. Moreover, the objectionable foamingtendency characterizing so many of the antistatic agents heretoforeprovided in the art, is in no way evident, and thus a highly efficientdegree of solution, e.g., developer, contact with the photographicemulsion is attained.

Results similar to those described above are obtained when theprocedures exemplified are repeated but wherein the gelatin is replacedtotally or partly with other film-forming organic binders eitherhydrophilic or hydrophobic in nature. In thosev instances whereinWaterinsoluble, alkaline-soluble resinous materials are employed, thebacking layer is of course temporary in nature. Despite the presence ofanti-halation dyestuffs, the backing layer may be permanently afiixed solong as such dyestuffs be readily convertible to a colorless, or leucoform so as not to interfere with viewing or projection of the reproducedimage.

The present invention has been disclosed with respect to certainpreferred embodiments thereof, and there will become obvious to personsskilled in the art, various modifications, equivalents, or variationsthereof which are intended to be included within the spirit and scope ofthis invention.

What is claimed is:

1. A photographic element comprising a film base coated on one side witha light-sensitive gelatino-silver halide emulsion and on the oppositeside of said film base a backing layer comprising (a) a film-formingorganic binder and (b) an antistatic compound consisting essentially ofthe condensation product of an alkylene oxide having from 24 carbonatoms with 2,4,7,9-tetramethyl-S-decyne 4,7-diol, said condensationproduct having a molecular weight of at least 300.

2, A photographic element as defined in claim 1 wherein the alkyleneoxide component of the antistatic compound is ethylene oxide.

3. A photographic element as defined in claim 1 wherein the film-formingorganic binder of the backing layer is gelatin.

4. A photographic element as defined in claim 1 wherein the backinglayer further contains an antihalation dyestuff.

References Cited UNITED STATES PATENTS 6/1966 DerSch 96 1l4 X 4/1969Knox 96l14.5

OTHER REFERENCES RONALD H. SMITH, Primary Examiner US. Cl. X.R.

